Fancy fuel-economy gauges are so popular in gas-electric hybrid vehicles that Toyota (TM) is studying whether they might provide a cheap way for drivers of its conventional cars to save gas as well.

"A group of engineers is looking at whether it makes sense to adopt to other cars," says Paul Williamsen, national manager of the product training facility for Toyota's Lexus division.

The gauge would show motorists when they are driving most efficiently, discouraging wasteful moves such as jackrabbit starts.

With automakers constrained in how fast they can bring out new engines and technologies to squeeze more economy from new models, they are increasingly looking at gauges and other stopgap measures. Many of today's cars already have indicators that show how many miles per gallon are being wrung from an engine at any given moment. In its hybrid vehicles, Toyota goes further.

Prius hybrid has an elaborate video display showing when the car is running on its electric motor or gas engine. Camry hybrid has a gauge that glows brighter when the car is running more efficiently. Lexus RX 400h and Toyota Highlander hybrid SUVs have a power indicator in the instrument cluster with a needle that shows when the truck is drawing the least or most electrical wattage, a possible model for a conventional-vehicle version.

Just how much gas can be saved by drivers who are fastidious about using the gauge depends on how they drive, Williamsen says.

Other automakers say the gauges make sense:

•Nissan. A fuel-efficiency meter started going into the instrument cluster of select Nissan and Infiniti cars, pickups and SUVs. It's going to be phased into the entire lineup. Nissan says the gauge can cut gas use by 10%.

•Ford Motor (F). Vehicles such as Ford Mustang, Edge and Fusion have a fuel-efficiency meter in the optional information center part of the instrument cluster. It denotes fuel use in a bar chart like the one denoting signal strength on cellphones.

•Chrysler and General Motors (GM). Displays show when cylinders are deactivated in the gas-saving systems of certain V-8 and V-6 engines. Chrysler vehicles show the message "fuel saver mode" on the instrument panel.

•Honda (HMC). Some models have a dashboard light that illuminates when gas mileage is optimal.

Toyota wants to find out if drivers will use the fuel-economy gauges. "For what percentage of buyers is it useful and what's the incremental (gas-mileage) improvement they get?" Williamsen asks. "Even if it we put it in all cars, some buyers might not care."

To report corrections and clarifications, contact Reader Editor Brent Jones. For publication consideration in the newspaper, send comments to letters@usatoday.com. Include name, phone number, city and state for verification. To view our corrections, go to corrections.usatoday.com.

Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more.